Re: is pivoted phones view updateable?

"Vadim Tropashko" <vadimtro_invalid_at_yahoo.com> wrote in news:1163183196.730989.262270_at_m73g2000cwd.googlegroups.com:

> This view is exactly the opposite of oldcontactview. While
> oldcontactview defines what data must be in the old table if we know
> the content of the new table, the newcontactview defines new table
> data if we know the old one. Yes, this view is definitely useful,
> especially if we want to migrate the data from old table to new one,
> but I have more advanced application in mind. I reserve new name for
> it - let's call it an inverse view, while the original oldcontactview
> would simply be a direct view. Formally, an inverse view is such a
> view that applying it after direct view will restore the content of
> the base table that the direct view uses in its declaration.

Let r1 = {'x' = x|x = 1..100}., v1 = {r1|x = 1..10}. One can not recover r1 from v1, it means v1 does not have the inverse. It means that a random view is not invertible in general. Received on Thu Nov 16 2006 - 22:21:05 CET